A passive optical network (PON) system is a kind of optical communications system. A PON system includes an optical line terminal (OLT), one or more optical network units (ONUs), an optical fiber to transmit an optical signal, and an optical splitter to allow the optical fiber to branch. The OLT is connected to the ONUs with the optical fiber and the optical splitter. The optical splitter is installed between the OLT and the ONUs. In this way, a plurality of optical network units can be connected to one optical line terminal.
The IEEE 802.3 standard prescribes the GE-PON and the 10G-EPON as standards of the PON. One of the differences between the GE-PON and the 10G-EPON is a transmission rate of data. The transmission rate of the GE-PON is 1.25 Gbps (bit per second). The transmission rate of the 10G-EPON is 10.3125 Gbps.
One PON system may include both the GE-PON and the 10G-EPON. An example of such a system is disclosed in Japanese Patent Laying-Open No. 2010-252044 (PTD 1).